6115 left 1.4 g (75 %) of triphenylphosphine oxide. The pentane solution was evaporated. The residue, 2.9 g of orange oil, exhibited a small peak at 4.71 p in the ir; there was a strong pyridine-like odor apparent. The oil was taken up in benzene and treated with anhydrous hydrogen chloride. Solvent was evaporated and the residue was washed with cold methanol. There remained 1.5 g (52%) of crude 14, mp 175". Recrystallization from ethyl acetate raised the melting point to 185-189"; ir N H peak at 2.96 p , strongest peak at 6.26 p ; nmr multiplet at T 2.5-3.4 (20) and a broad singlet at 4.7 (0.8). Aim/. Calcd for C2BH21C12N:C, 76.01; H, 4.79; c1, 16.03; N, 3.17. Found: C, 76.65; H,4.97; C1, 15.68; N,2.90. Treatment of 5 with Pyridine. Salt 5, 250 mg, was dissolved in 5 ml of pyridine. Evaporation of the pyridine resulted in recovery of the starting salt (ir spectrum superimposable on that of starting material). l,l-Diphenyl-4-p-nitrophenylbutatriene (16a). To a cold solution of 0.9 ml of triethylamine in 20 ml of acetonitrile was added 2 g of salt 5. After 5 min 492 mg of p-nitrobenzaldehyde was added. The mixture was allowed to stand at room temperature for several minutes and was then diluted with aqueous methanol. There was collected 1.3 g (69%) of cumulene 16a. Recrystallization from ethyl acetate afforded orange needles: mp 136-137"; ir (CHCla) 4.92 p (m), 6.32 (s), 6.67 ( s ) , 7.51 (s), 8.56(m),9.06 (s), 12.68p(s); nmr (CDCI,) doublet at T 2.0, multiplet at 2.6, singlet at 3.64, area ratio 2.1 :12.0:0.9. Anal. Calcd for CZ2HllN02: C, 81.21; H , 4.65; N, 4.31. Found: C,80.95; H, 4.67, N, 4.42. To a solution of 250 mg of salt 6, the allenylphosphonium bromide, in 5 ml of pyridine was added 77 mg of p-nitrobenzaldehyde. The mixture was heated 5 min on the steam bath and then diluted with aqueous methanol. There was collected 93 mg (61%) of 16a, mp 129-132", mmp (with 16a prepared from salt 5) 130-135". l,l-Diphenyl-4-(3,4-dichlorophenyl)butatriene (16b). To a cold solution of 0.9 ml of triethylamine in 20 ml of acetonitrilewas added 2 g of salt 5. After 5 min 570 mg of 3,4-dichlorobenzaldehyde was added. The mixture was allowed to come to room tempera-
ture and was diluted with aqueous methanol. There was collected 1.1 g of yellow needles, mp 109-111". Recrystallization from ethyl acetate afforded material with mp 113" dec; ir (CHCI,) 4.94 (w), 6.36 (s), 7.20 (m), 8.88 (s), 9.76 (s), 11.38 (s), 12.12 p (s); nmr (CDCl3)multiplet at 7 2.7, singlet at 3.71, area ratio 13 :I. Anal. Calcd for C22H14C12:C, 75.66; H , 4.04; C1, 20.30. Found: C,75.97; H,4.04; C1,20.05. N-Methyl-4,4-diphenyl-2,3-butadieneamide(18). To a solution of 2 g of salt 5 and 0.25 ml of methyl isocyanate in 15 ml of aceonitrile was added 0.7 ml of triethylamine. The mixture was heated 10 min and diluted with water. There was collected 230 mg (28 %) of crude allenamide 18, mp 189-191 '. Repeat recrystallization from chloroform-hexane raised the melting point to 192-193 '; ir (CHCI,) 2.96 (w), 3.39 (w), 5.21 (w), 6.06 (s), 6.65 p (m); nmr (CDCl3) singlet at T 2.76, singlet at 3.98, broad peak at 4.2, doublet at 7.2 (J = 4.5 cps) area ratios 10: 1 :0.8 :3. Anal. Calcd for CliHljNO: C, 81.90; H , 6.06; N, 5.62. Found: C, 81.72; H , 6.24; N, 5,79. The nmr spectrum in pyridine at 100" and chlorobenzene at 130" continued to exhibit the doublet at T 7.2; there was no coalescence of the peaks. Treatment of 5 with Diphenylketene. To a mixture of 2 g of 5 in 15 ml of acetonitrile was added 682 mg of diphenylketene prepared by the method of Staudinger. l 4 The solution was cooled to 0" and then 1.5 ml of triethylamine was added. The mixture was was stirred 10 min at 0" and refluxed 5 min. It was then diluted with water and extracted with benzene. The extracts were washed, dried, evaporated, and chromatographed on silica gel and alumina. There was obtained 222 mg (19%) of crude hydrocarbon, mp 205240 '. Recrystallization from benzene-hexane and benzenemethanol raised the melting point to 260-262"; uv 296 (log E 4.56), 370 mp (log e 3.77). The lit. valuesB are mp 260-262"; uv 297 (log E 4.88), 385 mp (log e 3.77). Anal. Calcd for CjsH4a: C, 94.53; H , 5.47; mol wt, 737. Found: C , 94.44; H, 5.46; mol wt, 730. (14) H.Staudinger. Chem. Ber., 38, 1735 (1905).
Formation of Pyridinium Ylides and Condensation with Aldehydes K. W. Ratts, R. K. Howe, and W. G . Phillips Contribution f r o m the Monsanto Company, Agricultural Division, Research Department, St. Louis, Missouri 63166. Receioed May 10, 1969 Abstract : Deuterium-exchange studies of N-methylpyridinium salts indicate that the 2 and 6 ring protons exchange more rapidly t h a n the N-methyl protons under basic conditions which give no detectable exchange of the 3, 4, a n d 5 ring protons. However, under the same conditions condensation of these salts with aldehydes occurs exclusively at the N-methyl position. Discussion of these results is given in terms of formation of intermediate ylides 1 and 2. Formqtion of either ylide 1 or 2 by decarboxylative methods i n the presence of aldehydes leads to direct condensation to give N-(2-hydroxy-2-arylethyl)pyridinium a n d 2-(a-hydroxybenzyl)-Nmethylpyridinium salts, respectively. These a n d other data are discussed a n d the conclusion drawn that the rate ratio of condensation t o reprotonation is greater for ylide 1 than-for ylide 2.
T h e reaction of ylidks with aldehydes has proven to be an extremely useful synthetic tool for the preparation of olefins (P ylides) and epoxides ( S ylides).' Consequently correlation and explanation of ylide reactivity is of considerable interest from the standpoint of synthetic utility. Pyridinium ylides are of some significance since (1) there exists no possibility for d-orbital stabilization of the carbanion and ( 2 ) two possible ylide structures may form (1 and 2). Condensation of pyridinium ylides (1) A. W. Johnson, "Ylid Chemistry," Academic Press, New York,
N.Y.,1967.
8 Nt
I
6H21
with aldehydes, contrary to known reactions of P or S ylides, produces the corresponding alcohols. 2-4 (2) R. K. Howe and I
